The best free PC games

Welcome to our round-up of the best free games on PC. As of March 2015, we've expanded our list from 50 to 75 to give you even greater choice. Think of this list as the perfect procrastination hub, packed with diversionary treats. Some are short and sweet, like Gravity Bone, some may consume you for weeks, like Spelunky.

All of the games on this list are free in their entirety. That means no microtransaction-supported free-to-play games and no shareware. We've also excluded 'pay what you want' games on the basis that developers who give you the ability to chip-in would probably like you to consider doing that. That said, there are always exceptions and you'll find games on this list that sit in a grey area – normally where there's a substantial free version with the option of also buying an upgraded paid edition. In these cases, we've gone with our hearts. Which is to say that we argued about it for hours.

Once we'd assembled our longlist we all voted for the games we liked the most and tallied up the scores to produce the list. The top games are the ones that have had the biggest impact on us, but that doesn't mean you won't find gems further down the list.

75. Refunktion: Episode 1

Phil: Refunktion is a momentum-based first-person platformer that's part stealth, part Mirror's Edge and, most of all, an absolute bastard. Your job is to collect the power cores scattered around each level – running, sliding and wall-jumping to avoid the patrol-bots hunting you down.

There are two approaches. You can take things slow, using vents and cover to avoid being seen; or you can make a run for it, maneuvering around, under and over your enemies in an attempt to be too quick to kill. The latter is naturally more fun, but requires a level of skill I'm as yet unable to match.

The robots are a relentless foil. The slow, inevitable charge of their lasers provides just a small window of escape. Fail to break line-of-sight in time and you're instantly killed – forced to restart from the last checkpoint. It's frequently frustrating, and requires plenty of trial-and-error tactics. Despite all this, there's lots to appreciate. With a good build-up of momentum, Refunktion's satisfying freerunning makes up for its faults.

74. S.W.A.P.

Phil: Swap, or Subterfuge Weapons Assessment Program, is a multiplayer twitch-based arena shooter that doesn't contain any guns. Instead, you fire your robot's hand at other players. If you hit, you'll swap places.

This is disorientating, and potentially deadly. For instance, if you've activated a trap, the person you swap with will then be killed by that trap. At least, they will if you hit them. Each map contains multiple hazards, punishing the unwary, as well as the recently swapped.

The player count is, unfortunately, a bit slim. Bring some friends to try it out.

73. Atom Smasher

Phil: "It's pretty straightforward, you probably won't need a tutorial," says the creator of Atom Smasher in his tutorial video (www.bit.ly/ASTutorial). That proved to be a massive overestimation of my ability to understand particle physics. After watching the tutorial, though, the game became a lot clearer. At its most basic level, it's a bit like Pipe Mania if Pipe Mania's ultimate goal was to unlock the secrets of all existence.

Your job is to build a series of increasingly complex particle colliders in an attempt to achieve each level's target speed. In the beginning, this is relatively simple. You add in some Microwave Klystrons, wire them up, and watch the MeV rating increase.

Soon, though, wiring becomes an issue. The game will always select the wire closest to the wall from the selection running above the machine. To combat this, you need to pull away unneeded cables, ensuring the correct colour matches the correct socket.

There's no penalty for it being wrong, other than the machine not working. At its core, Atom Smasher is a clever yet gentle puzzle draped in a science wrapping.

72. Fork Parker's Holiday Profit Hike

Phil: A word of advice to any aspiring CFOs: if your company's revenue is down for the year, releasing a free 2D platformer probably isn't the best solution. Luckily for Devolver Digital, the financial crisis depicted in Fork Parker's Holiday Profit Hike is as fictional as its protagonist. In it, the publisher's balding mascot Fork takes a break from his regular duties – cameoing in Serious Sam games and tweeting at Notch – to climb a nightmarish land filled with money, jagged icicles and deadly Christmas jumpers.

Your job is to collect as much money as possible while avoiding the many hazards hindering your ascent. To help achieve this you can throw out pitons: metal spikes that attach to surfaces to form a rope that extends between each subsequent piton placement. It's still extremely difficult, and every death results in unwanted medical bills that chip away at your possibly holiday profit.

71. VVVVVV – Make and Play Edition

Phil: Terry Cavanagh's VVVVVV has been infuriating paying customers for years. Now, a version of it has been made available for free. Bad news: it doesn't contain the base game. Good news: that means you won't have to destroy keyboards while trying to complete its Veni, Vidi, Vici section.

Make and Play is a special edition of the gravity-flipping platformer that includes only the game's level editor and a selection of user created maps. As such, there's a huge amount of content to be played, even without the original campaign. These aren't single-room challenges, either – there are sprawling, multi-segment creations to tackle. The totality of it dwarfs what VVVVVV originally offered, although, if you own the main game, these player creations are also included as part of that package.

As always, your job is to collect trinkets and crew members across an 8-bit world of bizarre hazards and repeating geometry. Many of the user-made maps continue the intricate difficulty of the original's gravity-based challenges. Progress is hard won, but the community has embraced the spirit of VVVVVV's generous checkpointing. Even the most difficult sections need only be conquered the once.

70. I Know This

Tom: There's a great bit in the original Jurassic Park where Lex infiltrates the park's security system, using what looks like another ridiculous mockup Hollywood hacking program. Well, it turns out this 'File System Navigator' was actually a real thing: a cool, and probably wildly impractical, way to explore a 3D representation of your PC.

Because we deserve it, a bunch of indie developers decided to turn this system into a real hacking game. The results are robust, tense, and a little bit gorgeous – hard drives seem so much bigger when their contents stretch out into the horizon.

Inspired by the ace hackertyper.net, the actual 'hacking' part of the game happens largely automatically, meaning you unlock files by randomly hammering at your keyboard. Occasionally, an Office Assistant-style paperclip will appear at the side of the screen, offering sound advice while wagging his finger at your law-breaking ways. It might seem a slim game beneath the slick presentation and that pleasing movie reference, but once you dig deeper into its mainframe, I Know This lives up to its inspiration and then some.